Conversion of positive to negative chemotaxis by Ca2+ ionophore treatment in plasmodium of Physarum polycephalum.
The plasmodium of Physarum polycephalum was treated with Ca2+ ionophores A23187 or X-537A, and the effects on the chemotactic and contractile activities were studied by applying a double-chamber method and an optical method. (1) At low Ca2+ concentration, attractants (glucose, L-alanine) KH2PO4) remained as attractants and induced a relaxation in the plasmodial strand. Increase in the external Ca2+ level caused a contraction of plasmodium with the same stimuli, and hence converted the attractants to repellents. (2) This phenomenon was specific to Ca2+; Mg2+, Sr2+ or Ba2+ showed no appreciable effects. (3) Repellents (sucrose, KCl, Quinine) induced a contraction, which was not altered by the Ca2+ ionophore treatment. (4) Efflux of Ca2+, which was measured by chemiluminescence of aequorin, increased on glucose reception in the presence of ionophore.
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000001:Calcimycin / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D002633:Chemotaxis / Q000187:drug effects*; D007832:Lasalocid / Q000494:pharmacology*; D008954:Models, Biological; D009068:Movement / Q000187:drug effects; D010804:Physarum / Q000187:drug effects* / Q000502:physiology
D000900:Anti-Bacterial Agents; D000001:Calcimycin; D002118:Calcium; D007832:Lasalocid